In a dental therapeutical field, a variety of tools are required. Most of these therapeutical instruments are applied with energies in some different forms such as air, water, electric power, light and the like. A handpiece for cutting teeth requires compression air for rotating a grinder at a high speed and high pressure water used for cleaning. An ultrasonic therapeutical instrument having a cutter blade or a scaler requires a high frequency power source for driving an acoustical transducer for producing high frequency vibrations at an operating end thereof, and a photo-radiator for producing a photo-polymerization of a dental resin requires a visual beam. Recently, a polishing powder jet flow for polishing the surface of teeth and a laser beam source for a coagulator are also required. Generally, there are many forms and kinds of final energies required but ultimate energies sources are high pressure air and high pressure water. Electricity is considered to belong to an intermediate energy form since it can be generated by other energy source, i.e., high pressure air or high pressure water. Even therapeutical instruments of the different types which consume the same kind of energy, the rating of energy thereof is usually different. Thus, in order to individually actuate many therapeutical instruments, energies in the form suited to these instruments, respectively, have to be supplied, as a consequence of which a dental therapeutical room is unavidably equipped with many energy supply units of the same kind. In this case, if different types of therapeutical instruments having the same energy supply unit are to be provided, this can be attained by providing each therapeutical instrument with an adapter which converts an energy received from the aforesaid supply unit into one suited to the therapeutical instrument. However, such a measure poses a disadvantage that individual therapeutical instruments become large-sized, which is not tolerable for a dentist. In many dental therapeutical rooms, there are provided some supplies comprising a combination of high pressure air and high pressure water, and a dentist connects a desired therapeutical instrument to a selected one of supply ports. Usually, a supply port is installed on a dental chair or an operating arm extended therefrom. Three to five ports are provided, and a therapeutical instrument having a different type or rating is selectively connected to each of such supply ports. The supply port in combination of high pressure air and high pressure water is made in the form of a quick engagement or a releasable connector, on which a power channel is also provided. Various types of connectors applicable to such supply ports are known, typical examples of which are disclosed in the following:
Japanese Patent Publication No. 45-30434 PA1 Japanese Utility Model Publication No. 39-24590 PA1 Japanese Utility Model Publication No. 50-11347 PA1 Japanese Utility Model Publication No. 50-11348 PA1 Japanese Utility Model Publication No. 50-15903 PA1 Japanese Utility Model Publication No. 50-15196 PA1 Japanese Utility Model Publication No. 54-27279 PA1 Japanese Patent Laid-Open No. 58-4546 PA1 Japanese Patent Laid-Open No. 58-5588